Elon Musk wants you to use Signal instead of Facebook.

Elon Musk — known as widely for slinging cars into the sun’s orbit as he is for advocating against Covid-19 safety measures — took to Twitter last week to slam Facebook over its latest privacy policy updates for its supposedly secure encrypted messaging app WhatsApp. Musk instead recommended users choose encrypted messaging app Signal.

The tweet was then retweeted by Twitter CEO Jack Dorsey. Shortly after, Signal tweeted that it was working to handle the surge of new users.

Musk’s Twitter endorsement also incidentally led shares in the biotechnology company Signal Advance to soar, despite the fact that it is completely unrelated to Signal, which is not a publicly traded company.

This isn’t the first time Musk has publicly sparred with Facebook over privacy concerns. In 2018, he not only had his own personal Facebook page removed, but those of his companies Tesla and SpaceX. His take on the long-fought battle between Signal and WhatsApp isn’t off-base, though.

Both of the encrypted messaging apps have been found to have security bugs over the years that have been resolved. For years, WhatsApp has openly collected certain user data to share with parent company Facebook. Its latest policy change just expands that. Signal, on the other hand, has a history of fighting any entity that asks for your data, and adds features to further anonymize you where possible.

What Signal is, and how encrypted messaging works

Signal is a typical one-tap install app that can be found in your normal marketplaces like Google’s Play Store and Apple’s App Store, and works just like the usual text messaging app. It’s an open source development provided free of charge by the non-profit Signal Foundation, and has been famously used for years by high-profile privacy icons like Edward Snowden.

Signal’s main function is that it can send text, video, audio and picture messages protected by end-to-end encryption, after verifying your phone number and letting you independently verify other Signal users’ identity. You can also use it to make voice and video calls, either one-to-one or with a group. For a deeper dive into the potential pitfalls and limitations of encrypted messaging apps.